Detection: USN Journal Deletion

Description

The following analytic detects the deletion of the USN Journal using the fsutil.exe utility. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process execution logs that include command-line details. This activity is significant because the USN Journal maintains a log of all changes made to files on the disk, and its deletion can be an indicator of an attempt to cover tracks or hinder forensic investigations. If confirmed malicious, this action could allow an attacker to obscure their activities, making it difficult to trace file modifications and potentially compromising incident response efforts.

Search

 1
 2| tstats `security_content_summariesonly` 
 3  count values(Processes.process) as process 
 4        values(Processes.parent_process) as parent_process 
 5        min(_time) as firstTime
 6        max(_time) as lastTime 
 7
 8from datamodel=Endpoint.Processes where 
 9
10Processes.process_name=fsutil.exe
11Processes.process = "*usn*" 
12Processes.process = "*deletejournal*"
13
14by Processes.action Processes.dest Processes.original_file_name Processes.parent_process
15   Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id
16   Processes.parent_process_name Processes.parent_process_path Processes.process Processes.process_exec
17   Processes.process_guid Processes.process_hash Processes.process_id Processes.process_integrity_level
18   Processes.process_name Processes.process_path Processes.user Processes.user_id Processes.vendor_product
19
20
21| `drop_dm_object_name(Processes)` 
22
23| `security_content_ctime(firstTime)`
24
25| `security_content_ctime(lastTime)`
26
27| `usn_journal_deletion_filter`

Data Source

Name	Platform	Sourcetype	Source
CrowdStrike ProcessRollup2	N/A	'crowdstrike:events:sensor'	'crowdstrike'
Sysmon EventID 1	Windows	'XmlWinEventLog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Windows Event Log Security 4688	Windows	'XmlWinEventLog'	'XmlWinEventLog:Security'

Macros Used

Annotations

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Implementation

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

None identified

Associated Analytic Story

• Ransomware

• Windows Log Manipulation

Risk Based Analytics (RBA)

Risk Message:

Possible USN journal deletion on $dest$ via $process$

References

• https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/fsutil-usn

Detection Testing

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 8